The Orionids meteor shower 2018

This year the Orinids meteor shower peaks in the predawn skies of October 2st. Orion will be in the south around 4:30am BST an hour after the Moon has set and several hours before Sunrise. The meteors can appear in any part of the sky, but if you trace them back they will appear to originate from the constellation of Orion. For the best views look to the sky about 45 degrees on either side of the constellation from a dark sky location.

The meteors are caused by the Earth moving through the trail of debris left by Comet Halley.

Clear skies

Draconid meteor shower 2018

The Draconids meteor show peaks on the evening of Monday 8th October. See below for a sky chart. The radiant is in the West North West, the best time to look being in the early evening, after 8:30pm BST.

The Draconids are the result of debris from comet 21P/Giacobini-Zinner which will pass close to the Seagull Nebula in the early hours of Tuesday morning, a great photo opportunity.

Clear skies.

Report from our observing session on the 4th October

Well the season has gotten off to a good start, the first observing session scheduled for the year and we are not clouded off as usual!

The new site seemed to be as good, if not better than our old site, slightly less light pollution from Abingdon, but possibly affected by the car lights a little more (if I am to be picky), not as good view to the West but much better to the East and North from the end of the car park we Observed from.

There was 8 of us altogether with 5 telescopes and several pairs of binoculars.

Trevor with his 5” refractor, Keith and Jason both had 8” Celestron Edge HD scopes, Graham had a Celestron C90 and I took my 6” RC. Cristina also had her 15 x 70 Celestron binoculars.

We started off looking at Saturn which was only visible for a few minutes before dipping below some trees to our south west. The rings are in a favourable position at the moment, giving us a lovely view (even if it was only for a few minutes).

Next target was mars, although very bright, it was not a particularly impressive view.

We then attempted to go through some the Deep Sky list that was in the September Space Watch, plus a few others.

M13 Globular Cluster in Hercules, M15 GC in Pegasus and M2 GC in Aquarius.

The Veil Nebula through Trevor’s refractor with an Oxygen 3 filter.

M27 The Dumbbell Planetary Nebula in Vulpecula

M31 Andromeda Galaxy and its 2 companion galaxies M32 and M110

M81 and M82 Bodes Galaxy and the Cigar Galaxy in Ursa Major

M45 The Pleiades, Open Cluster

NGC 869 and NGC 884 The Double Cluster in Perseus

And another Galaxy that Trevor showed us, that I cant remember the name of (but I will edit it in to the report later and no one will be any the wiser 😉)

Altogether it was a very enjoyable evening, clear skies for the duration, lots to look at and nice to get a look through some different scopes and eye pieces.

Hope to see more of you at the next one.

Clear skies

The Moon buzzes the Beehive

One for the early risers, the Moon will be less than 2 degrees from M44, the Beehive cluster in Cancer in the early hours of Thursday 4th October. Closest approach is around 6am BST.

Unfortunately comet 21P/Giacobini-Zinner will probably be lost in the pre dawn sky and glow from the Moon.

Clear Skies

Opposition of Saturn

Saturn comes to opposition on the 27th June 2018. Unfortunately for UK observers it doesn’t get very high in the sky being just above the teapot asterism in Sagittarius:

But if you can get to see it, the rings are nice and wide. Note, that Mars is also rising and will reach opposition next month.

Clear skies.

May’s AGM talk

For those of you who missed the AGM, Themos Tsikas tried to squeeze a full length talk into an after tea space. Sadly, time dilation did not work, even though he blue shifted near the end. Perhaps we should try to list the variety of hobbies our members have, besides astronomy. We have now found out that Themos is a very keen sailor.

So he approached his talk from a sailing point of view, and really only hit on the astronomical side at the end.

So, basically you are on a boat on a globe, much of it sea. How do you keep your bearings? Easy if you know what time it is and you can see how high the Sun, Moon, or certain stars are. But that only gives the latitude, not the longitude.

The simplest way is to think of yourself looking up at the sky, hopefully clear(ish) of clouds. At night you should see lots of stars, and these will all be overhead somewhere as seen from Earth. You use a sextant to work out the angle of altitude of certain known stars and imagine a line starting from your position, going round their zenith point and coming back to you. You then wait ten minutes and remeasure. The circle will have changed, unless you happened to pick on Polaris…. If you use the Sun or the Moon, it is not so easy, because of their larger proper motion. You can then work out the circles’ intersection points and that’s where you are. You must also make sure not to crouch or climb onto a higher point to take readings, as that alters the object’s height above the horizon.

Themos did not get as far as the list of navigational stars, of which some have intriguing names (Needless to say, Polaris is not among them.). He did have two sextants, and showed us how to line up the moving mirror (which is linked to the scale via a sliding arm) so that the horizon is lined up with a star, Moon or Sun, thereby giving the altitude.

Please Themos, do bring those lovely gadgets again so we can have another play with them during the tea break. Time ran out on you too soon. At least you had time to show us a quick video of how to use a sextant.

Clear skies

April’s talk

“ALMA”

Neil Philipson is one of those useful people to know, as he clearly has a passion for his topic.  He called himself a designer and telescope seller.

His pet subject is the ALMA setup in Chile, namely the Atacama Large Millimetre Array.

It was completed in 2013 and consists of 66 12metre radio dishes, and these are through a collaboration of Europe, USA and Japan/East Asia.  Europe and the USA provided 25 each, then Japan tacked on another 16 later; these are a grouping of four 12m dishes and 12 seven metre dishes and are called the ‘Compact Array’.  So this is now all called ‘Enhanced ALMA’

He calls it ‘supercomputer astronomy’ and says it’s the largest collection in history.

So why choose microwave collectors?  After all the wavelengths are a thousand times longer than the visual stuff, so the collectors have to be huge, in theory, to get the same resolution as our optical telescopes.  These millimetre and sub millimetre wavelengths radiate from stuff that is close to absolute zero.  This is the oldest stuff in the universe.  You can also include early stage galaxy formation and nebulae which are in the early stages of forming stars.  They radiate in these wavelengths.

Mr Philipson then came onto location.  Our atmosphere blocks most of the radiation at this wavelength so why wasn’t ALMA chucked into space?  (His words). Basically because of the expense, and at 5000m altitude, you can get above most of Earth’s atmosphere and you still get the resolution.

Extravagant suggestions were made for the original location.  After all, you had to have stable, very dry air, and it had to be cool and far away from people.

So, Greenland, the Himalayas and even the South Pole were among the original choices.

The Llano de Chajnantor was finally chosen, 16,500 feet up.  For its trouble, Chile gets 10% observing time.  (Japan gets 15% and Europe and the USA share the rest equally.)

So these 66 dishes have a fairly free rein up there, although they are posted in clumps and have parking pods too.  They are linked by fibre optics to an accuracy of a millionth of a millionth of a second.  (In the same way that we have the very long baseline interferometry of the longer wavelength radio telescopes such as the MERLIN or VLA complexes)  At their biggest separation they have a 16km diameter but can be gathered into a 250m diameter.  At their biggest separation they have a resolution down to 0.004” (arc seconds), which is ten times that of Hubble.  In compact formation, the field of view is 50”, at expanded, it is 1.25″

The dishes are figured to one fortieth of a wavelength of what they’re looking at.  The collecting receivers are in a hole in the middle of each dish and they have to be cooled to 4 kelvin, because the stuff they’re observing is so cold and you don’t want the receivers radiating heat.

Mr Philipson lamented that the achievements of ALMA are not publicised much, but ALMA has been able to see beyond  a very distant galaxy cluster to a time only 200 million years after the Big Bang.  He mentioned the ’Sunyaev-Zel’dovich effect’  which is seen in early galaxies interacting gravitationally, producing hot gas and distorting the cosmic microwave background.  (The CMB is the radiation from the Big Bang.)

Most intriguing is its observations of Betelgeuse, whose diameter has shrunk since it was possible for us to resolve the disc.  (It is about a half arc second across.)  It also has a plume of gas bigger than our Solar System, and the fact that is shrinking so quickly indicates that it is going supernova in the next 100,000 years, if it hasn’t done so already.

If anyone comes across any interesting finds, let us all know, especially those where Mr Philipson says multiple rotations of the Earth were needed to get enough information because of the faintness.  Also, decent pictures of the Array seem lacking.

Clear Skies.